Sectional upward acting doors are ubiquitous in applications for cargo bodies of freight vehicles, including motor trucks, for example. Mobile cargo bodies are, of necessity, fabricated of components which are required to be as light in weight as possible in order to reduce the tare weight of the vehicle. However, such components must also be of sufficient structural integrity as to not fail in normal use. Sectional upward acting doors for cargo bodies are preferably manufactured of lightweight extruded materials including aluminum and plastics. One problem associated with the design and manufacture of sectional doors for cargo bodies pertains to the stiffness of the door panels required to resist damaging deflections due to rough treatment, wind loads and impacts from shifting cargo. A related problem with regard to cargo pertains to that wherein cargo items may shift during transport and lodge against the inside surface of the door and engage with projections, such as hinge components and the like which can prevent opening the door.
Accordingly, there has been a need to provide lightweight sectional doors for cargo bodies and the like which can be conveniently reinforced, when needed, by reinforcing members which in themselves are lightweight while adding the requisite rigidity to the door panels and wherein the reinforcing members do not aggravate but alleviate problems associated with cargo shifting against the door which would prevent the door from being opened. It is to these ends that the present invention has been developed.